<template>
<div>
	<router-link 
		class="header-abs" 
		v-show="showAbs"
		tag='div' 
		to='/'>
		<div class="iconfont header-abs-back">&#xe624;</div>
	</router-link>
	<div class="header-fixed"
		v-show="!showAbs"
		:style="opacityStyle"
		>
		<router-link to='/'>
			<div class="iconfont header-fixed-back">&#xe624;</div>
		</router-link>
		景点详情
	</div>
</div>
</template>

<script>
	export default {
		name:'DetailHeader',
		data(){
			return {
				showAbs:true,
				opacityStyle:{
					opacity:0
				}
			}
		},
		methods:{
			handleScroll(){
//				console.log(document.documentElement.scrollTop)
				const top = document.documentElement.scrollTop
				if(top>60){
					var opacity = top / 140
					opacity = opacity > 1 ? 1:opacity
					this.opacityStyle = {
						opacity
					}
					this.showAbs = false
				}else{
					this.showAbs = true
				}
			}
		},
		activated(){
			//全局事件绑定 
			window.addEventListener('scroll',this.handleScroll)
		},
		deactivated(){
			window.removeEventListener('scroll',this.handleScroll)
		}
	}
</script>

<style lang="stylus" scoped>
@import '~style/varibles.styl'
	.header-abs {
		position: absolute;
		left: .2rem;
		top: .2rem;
		width: .8rem;
		height: .8rem;
		line-height: .4rem;
		border-radius: .4rem;
		background: rgba(0,0,0, .8);
	}
	.header-abs-back {
		color: #fff;
		font-size: .4rem;
		text-align: center;
		height: .8rem;
		line-height: .8rem;
		
	}
	
	.header-fixed {
		z-index: 2;
		position: fixed;
		top: 0;
		left: 0;
		right: 0;
		height: .86rem;
		line-height: .86rem;
		text-align: center;
		color: #fff;
		background-color: #00bcd4;
		font-size: .32rem;
	}
	.header-fixed .header-fixed-back {
		position: absolute;
		width: .64rem;
		text-align: center;
		font-size:.4rem;
		color: #fff;
	}
</style>